This invention relates to a gas delivery system, particularly, although not exclusively, one for use in dry processing apparatus, for example one in which a switched etch/deposition cycle or continuous process is used on a semiconductor wafer or the like.
Continuous plasma processes as well as switched etch/deposition processes use sulphur hexafluoride as the standard etch chemistry. The industry demands for higher etch rate processes have led to the investigation of alternative process etch gases which allow an increase in the density of active species in the process chamber resulting in improved process rates.
Several different chemistries are known to be likely candidates to enhance the process rate. All suffer from increased cost, greater health and safety risks and poor commercial availability. These factors combine to make the economics of implementing these chemistries extreme and/or the installation too hazardous. Latterly, a number of molten electrolyte gas generators have been reported and are just being made commercially available. Generation of gases by this means includes fluorine, nitrogen trifluoride and chlorotrifluoride. An example is a fluorine gas generator cell as described in U.S. Pat. No. 5,688,384. The generators are able to generate the process gases to high purity and at a reasonable cost and risk. The gas generators contain a solid when cold and this allows for safe transportation and storage of the units.
The incorporation of these gas generators into a gas delivery system local to the process chamber allows a novel capability to introduce different processes gases into a variety of process schedules to achieve a process advantage. There are many novel aspects to the application of these gas generators to a dry processing environment in terms of system design, gas delivery control, system transportation, ease of installation and process advantages.
Thus, according to a first aspect of the present invention there is provided an apparatus for treating a substrate, the apparatus comprising a chamber, a support for a substrate and a delivery system for delivering an etchant and/or a deposition gas into the chamber, wherein the delivery system is positioned locally to the chamber.
xe2x80x9cLocallyxe2x80x9d (or point of use) means that the delivery system is located near to a process chamber or a number of chambers or number of systems near to one another, so that the gases created can be delivered directly to the chamber or system for immediate use rather than being created off-site and transported in a suitable container for subsequent introduction into the apparatus.
The delivery system will preferably include a molten electrolyte gas generator